Getting ready to do a lift and wonder which one you think works better on old rusty bolts.

 

I've heard people pledge allegiance to both of them....have seen some especially back east in the US where everything seems to rust out, use mostly Kroil. best course with either one is hit it good... then let it soak for awhile maybe even overnight depending on how bad they are. Then hit it again with a liberal amount.
If that doesn't work, there's always heat.

 

Or you can mix some acetone and atf (50/50) and make your own. Grab a torch while you're at it.

At the risk of igniting another cyberwar, I use PB Blaster.

 

I've got both PB Blaster and Kroll between those 2 I like the Kroll but way more pricey. HOWEVER my usual go to is ATF and Acetone and heat!